The invention relates to a camshaft adjusting device, in particular a passive camshaft adjusting device of an internal combustion engine with at least three shafts and a gear mechanism.
It is known to change the phase position of a camshaft of an internal combustion engine by passive, i.e. driveless camshaft adjusting devices. These devices comprise, for example, a brake and a lever mechanism, as it is known from Laid-open specification DE 102 47 650 A1. The variable moment of the brake at the control input of the adjusting gear mechanism of the camshaft adjusting device leads to the change of the phase position of the camshaft. Application of the brake causes the control shaft to slow down so as to change the phase position to advance valve timing, for example, via a negative gear mechanism. If the brake is released, the control input accelerates because of the load moment of the camshaft, and the phase position is changed to retard the valve timing. At a constant phase position, the control shaft has to be kept to the rotational speed of the camshaft in such a manner that no relative movement in the adjusting gear mechanism is possible.
During startup of the internal combustion engine, at low rotational speeds and when the brake fails, the camshaft adjusting device has to be locked in a position customarily situated between end stops. Locking is also desirable in the event of failure of parts of the system, such as the brake, the control unit, the contact connection means, the sensor technology and the like, in order to permit emergency operation of the vehicle.
It is the principle object of the present invention to provide a camshaft adjusting device with which reliable locking of the camshaft adjusting device is possible in a cost-effective manner.